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Location and Background
The Gaoua project covers 750km² within the prolific Boromo greenstone belt, an early Proterozoic Birimian sequence of the West African Craton.
The project includes the 100%-owned, contiguous Malba, Souhouera and Danyoro permits, which hosts numerous copper-gold and gold prospects previously identified by historical aid programs. These permits cover about 35km in strike length of the prospective structural corridor that hosts most known copper-gold and gold occurrences. The three permits lie approximately 70 km northeast of Volta's Kampti permit.
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Review of the historical exploration data, along with current exploration efforts, confirm classic porphyry-style mineralization, relatively enriched in gold.
An abundance of artisanal workings, extensive copper soil anomalies, coincident gold stream sediment anomalies, high magnetic susceptibility targets and induced polarization (IP) conductors suggest potential extensions of the current copper-gold mineralization. The Gaoua project make up a highly prospective porphyry copper-gold terrain that, until recently had not been explored using modern methods.
The region has established infrastructure including highways, plentiful water sources nearby, good power and telecommunication networks, and has historically been a major artisanal gold producing area of Burkina Faso.
Geology and Mineralization
The major geological units strike north-south. They include basaltic and andesitic rocks, together with volcaniclastic units and chemical sedimentary rocks (chert and quartzite). These units are intruded by diorite and dioritic breccia units.
Within the Malba and Souhouera Permits, there is a central structural corridor that hosts most known copper-gold and gold occurrences. Among those are the main prospects of Gongondy, Dienemera and Mt. Biri. These prospects contain mineralization hosted in various phases of the dioritic intrusive units.
The mineralization at all three of the drilled prospects is associated with a hydrothermal breccia that is largely hosted by diorite porphyry intrusions, though it locally extends into the adjacent volcanic tuffs. The Cu-Au mineralization is however usually confined to the dioritic porphyry dominated area. The mineralized breccia is characterized by small clasts and by the presence of centimetric clots of cementing minerals that approximate a triangular form. The hydrothermal cement is composed of quartz, K-feldspar, epidote, chalcopyrite, pyrite, calcite and anhydrite. Open cavities occur in core recovered from above the sulphate front, thereunder anhydrite is an important late cementing mineral. Most of the breccia-hosted mineralization consists of hypogene chalcopyrite with which gold values appear to be closely correlated.
Important isolated gold highs which are not immediately associated with the copper mineralization are frequently observed in the drill holes (see further). This gold mineralization appears to be related to mineralized veins which may post-date the Cu-Au sulphide mineralization phase.
Exploration Strategy
Stream Sediment and Soil Sampling
Stream geochemistry (Bulk Leach Extractable Gold) is used as an initial reconnaissance tool to outline potential areas of interest within the permits. A soil sampling program was used over the corridor of higher values outlined by the stream sediment sampling.
Soil sampling has been used in the core area of the Malba and Souhouera permits to cover, and attempt to extend, the known mineralization. An area of about 49 km2 has been tested. Samples were collected on east-west lines spaced at 200 m and samples were collected at stations spaced 25 to 50 m. The survey has outlined several anomalous areas that require follow-up.
Trenching
Trenching was completed at Dienemera and Mt. Biri. The purposes of the trenches were to allow better inspection and verification of soil anomalies. The trenches were dug by hand using local labour. Trenches were dug to a 2 metre depth where possible. All trenches confirmed the presence of highly anomalous copper values.
Geophysical Surveys
Sagax Afrique S.A. (Sagax) completed ground geophysical surveys over the prospects of Gongondy, Dienemera and Mt. Biri. A total of 22 line-kilometres of gradient array and 5.0 kilometres of dipole-dipole array IP, and 22 line-kilometres of ground magnetic data were acquired during the geophysical survey over the three targets.
The gradient array IP survey and four IP dipole-dipole test lines conducted over the Gongondy prospect identified one large principal, north-south trending, chargeable anomalous corridor with a maximum response of approximately 15 mV/V (milliseconds) above background. The corridor is affected by NNW and NNE trends, and is open to the north and south. Drilling of the chargeability anomalies (see further) showed that the anomaly is caused by the abundant presence of pyrite, possibly representing a halo around the Cu-Au core.
The gradient IP survey and dipole-dipole test lines at Dienemera identified a series of chargeable anomalies, roughly oriented north-south. The two main anomalies are broadly coincident with the copper-gold mineralization, as mapped from the drilling campaigns, although the IP anomalies extend beyond the drill-tested areas and remain open for further surveying. The main anomaly, which shows a maximum response of approximately 15 mV/V (milliseconds) above background, coincides with the area where, among others, drill hole DIE76 intersected 78m @ 0.56% Cu and 0.22g/t Au from surface, 11m @ 0.46% Cu and 0.19g/t Au from 184m; 13m @ 0.34% Cu and 0.12g/t Au from 218m and 4m @ 0.80% Cu and 0.72g/t Au from 265m depth.
Further ground geophysical surveying is now planned over larger parts of the Malba and Souhouera permits. These surveys will aim at further defining new drill targets.
Drilling
In October 2007, a 41-hole, 12,626m diamond drill program was completed by the Company at the Gaoua project. The six-month program tested several targets in three main areas: Gongondy, in the Souhouera property; and the Dienemera and Mont Biri targets, in the Malba property. The campaign confirmed the presence of highly anomalous copper-gold mineralisation hosted by brecciated diorite and hydrothermal breccia, which show porphyry copper characteristics in all three target areas. Highlights of the campaign are shown in the table below.
Copper-gold mineralization at Gongondy has been intersected for more than 2km of strike length, while drilling at Dienemera has identified copper-gold mineralization over the entire tested area, extending north-south for over 900m by nearly 850m at its widest point. In both areas, mineralization remains open in all directions. Further drilling will be needed to test whether the mineralization is continuous, hosted by one large body, or in a set of contiguous breccia bodies.
Drilling at Mont Biri, 2km north of Dienemera, identified Cu-Au mineralization in previously-untested areas, opening new targets for further exploration. Four diamond drill holes have been completed at Mt. Biri and significant mineralization was intersected in two of them. The intersections target different areas of potential mineralization. As the Mt. Biri drilling is at an early stage, it is not possible to discuss potential size of any mineralized body that may be developed by further drilling.
Salient intersections of the drilling campaign are presented in the tables hereunder. The shapes of the mineralized bodies have yet to be fully determined. True thicknesses of mineralization cannot be determined at present.
SIGNIFICANT DIAMOND DRILL INTERSECTIONS AT GONGONDY
| Hole No. |
From (m) |
To (m) |
Length (m) |
Cu% |
Au g/t |
| S23GON/07 |
9 |
78 |
69 |
0.62 |
0.68 |
| S26GON/07 |
77 |
90 |
13 |
0.52 |
0.35 |
| S27GON/07 |
60 |
83 |
23 |
0.45 |
0.31 |
| 119 |
178 |
59 |
0.61 |
0.36 |
| Incl. |
170 |
177 |
7 |
1.80 |
0.75 |
| S32GON/07 |
184 |
300 |
116 |
0.37 |
0.25 |
| Incl. |
277 |
300 |
23 |
0.79 |
0.45 |
| S33GON/07 |
20 |
46 |
26 |
0.75 |
1.11 |
| 256 |
262 |
6 |
0.31 |
0.30 |
| 282 |
288 |
6 |
0.37 |
0.30 |
| S37GON/07 |
1 |
41 |
40 |
<0.1 |
0.54 |
S38GON/07
Incl. |
188 |
202 |
14 |
<0.1 |
1.16 |
| Incl. |
188 |
190 |
2 |
<0.1 |
5.27 |
| S39GON/07 |
0 |
8 |
8 |
0.43 |
0.26 |
| 113 |
119 |
6 |
0.52 |
0.28 |
SIGNIFICANT DIAMOND DRILL INTERSECTIONS AT DIENEMERA
| Hole No. |
From (m) |
To (m) |
Length (m) |
Cu% |
Au g/t |
S72DIE/07
Incl. |
88 |
145 |
57 |
0.41 |
0.21 |
| 125 |
145 |
20 |
0.59 |
0.29 |
| S73DIE/07 |
147 |
162 |
15 |
0.48 |
0.15 |
| S74DIE/07 |
7 |
12 |
5 |
0.49 |
0.23 |
| 38 |
49 |
11 |
0.46 |
0.14 |
| 74 |
81 |
7 |
0.38 |
0.14 |
| 158 |
191 |
33 |
0.37 |
0.13 |
| 283 |
288 |
5 |
0.40 |
0.17 |
| S75DIE/07 |
44 |
90 |
46 |
0.33 |
0.10 |
| 130 |
159 |
29 |
0.56 |
0.17 |
| 182 |
197 |
15 |
0.61 |
0.25 |
| S76DIE/07 |
0 |
78 |
78 |
0.56 |
0.22 |
| 184 |
195 |
11 |
0.46 |
0.19 |
| 218 |
231 |
13 |
0.34 |
0.12 |
| S77DIE/07 |
2 |
11 |
9 |
0.43 |
0.14 |
| 42 |
69 |
27 |
0.33 |
0.19 |
| 127 |
162 |
35 |
0.44 |
0.27 |
SIGNIFICANT DIAMOND DRILL INTERSECTIONS AT MT BIRI
| Hole No. |
From (m) |
To (m) |
Length (m) |
Cu% |
Au g/t |
| S45MBI/07 |
117 |
130 |
13 |
1.53 |
1.07 |
| S47MBI/07 |
181 |
186 |
5 |
0.72 |
<0.1 |
| 233 |
280 |
47 |
0.26 |
<0.1 |
| Incl. |
256 |
262 |
6 |
0.39 |
<0.1 |
| Incl. |
276 |
280 |
4 |
0.58 |
<0.1 |
All of the drilling was completed by West African Drilling Services, a subsidiary of Layne Christensen Company of the United States of America.
Additional Potential
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Geological mapping and soil geochemical surveying carried out in 2007 identified several copper-gold anomalies in the 8km separating Gongondy and Dienemera/Mont Biri, considerably expanding the potential in the area.
Stream sediment sampling carried out over the southern part of the Souhouera and over the entire Danyoro properties has identified several copper and gold anomalies along strike with the known Cu-Au mineralization of Mt. Biri-Dienemera-Gongondy, extending the area for further testing by several kilometers to the south.
Along this (southern) extension zone, some 5km south of Gongondy, occurs the gold artisanal site of Gomblora. More than 2,000 artisanal miners are currently exploiting gold from narrow quartz veins and altered host rocks. Gold is being mined from the abundant quartz veins and mineralized systems (shears) which occur essentially along the contact between basalts, gabbro and pyroclastics.
A sampling study aimed at determining the prospectivity of this area confirmed the widespread presence of high-grade gold mineralization. Out of the 71 collected grab samples 31 (43%) returned grades exceeding 1 g/t Au and 16 (22%) exceed 10 g/t Au. Most of the mineralized quartz vein material returned values above 1 g/t with peaks of 43, 67, 91 and 557 g/t Au respectively. The Gomblora gold mineralization is inferred to be related to the Cu-Au mineralizing system, possibly representing a higher level of the system.
Quality Control/Quality Assurance (QA/QC)
The Company maintains a QA/QC program in all of the sampling that it has undertaken. This program includes the use of reference samples, blanks and duplicates. Reference samples are included at a rate such that 5% of all samples sent for analysis are reference samples. Blanks are included at a rate of 3.3% of all samples and duplicate samples are included at a rate of 2%.
The company maintains close contact with the laboratory on matters regarding QA/QC.
Next Steps
The Company intends to carry out an aggressive drilling program, starting in the second quarter, followed by initial resource calculations on the Gongondy and Dienemerra deposits. The company plans further large geophysical surveys over the central mineralized corridor aimed at further defining Cu-Au drill targets.
Agreement with Freeport McMoRan Exploration Corporation
Volta currently has a definitive agreement with Freeport McMoRan Exploration Corporation (FMEC), a wholly- owned subsidiary of Freeport McMoRan Copper and Gold, whereby FMEC may earn up to a 70% interest in the Malba, Souhouera and Danyoro permits by funding the projects through completion of a feasibility study.
Under the terms of the agreement, FMEC may earn a 51% interest by spending US$5,000,000 over 3 years and making cash payments to Volta totaling US$225,000.
FMEC has spent over US$2,500,000 in the first year, during which time Volta was the operator.
Volta has the right to explore the properties for gold-only prospects at its own expense, under certain conditions.
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